FROM WIKI:
Luke and Laura went on the run with Frank's henchmen hot on their trail. One of the men named "Hitch" ended up befriending the two and could not kill them. The other hit man attempted to complete the hit but was discovered and killed by Hitch.
It turned out that with Frank's black book, Luke and Laura did indeed have the evidence they needed to send Frank to prison. In 1984, Frank framed Luke for a murder that was committed in Mexico and his best friend Robert Scorpio helped Luke was clear his name. Laura had just announced her first pregnancy and they are on the run once more. In 1993, Frank's hit men track Luke and Laura to the Triple L Diner in Canada and blew up their truck thinking they were inside. For safety reasons Luke and Laura send Lucky back to Port Charles to live with Luke's "aunt" Ruby Anderson. Frank's men found Lucky staying with his friend/cousin Sly Eckert. They also find Sly's father Bill Eckert, who is the spitting image of Luke. Bill is shot in a case of mistaken identity. He dies in Luke's arms.
Luke and Laura, with their son Lucky, decided to hide in plain sight, back in Port Charles. Damian Smith, on behalf of Daddy, promises Luke that he and his family will be safe if Luke will help smuggle people into the country, with Corinthos as a liaison. Luke says yes until he can figure out how to get rid of Smith. It turns out to be no easy task and puts him back in touch with a much-changed Jennifer. To get him out in the open, Luke helps spring Frank from prison in 1993.
This time Laura had announced her second pregnancy with (Lulu Spencer). Smith kidnaps a very pregnant Laura and uses her as a human shield and gets away. Lucky follows his father to a meeting with Frank's henchman and is shot but makes a full recovery. Finally, they at last have a final showdown at a cemetery in Puerto Rico in which Luke kills Frank. After Frank's death, Sonny Corinthos takes over his organization.